Load management auxiliary power system

ABSTRACT

An auxiliary power system for trucks, the power system having a small diesel engine coupled to an air conditioner compressor and an automotive style alternator. During hot weather the auxiliary engine rotates the air conditioner compressor to provide cool air to the truck and electrical power to truck accessories by load management controls. When peak loads occur, the voltage is reduced into the field of the alternator allowing the small engine to simultaneously operate the air conditioning compressor. During cold weather the engine coolant is used to cool the auxiliary engine and is circulated through a heat exchanger for warming of the truck interior. Full capacity of the alternator is allowed, accommodating the higher amp draws typical of cold weather diesel operation.

RELATED APPLICATIONS

This application is a continuation-in-part of applicant's co-pendingU.S. application Ser. No. 10/060,091 filed Jan. 29, 2002, the contentsof which are hereby incorporated by reference.

FIELD OF THE INVENTION

This invention is related to auxiliary power systems, in particular, toan auxiliary power system having a load shedding voltage regulator whichprioritizes air conditioning by reducing electrical power generation tominimize auxiliary engine size requirements, thus reducing space andweight requirements for the auxiliary power system.

BACKGROUND OF THE INVENTION

Total fossil fuel waste, and the associated economic waste, within thetrucking industry is staggering. It is estimated that six out of everyfourteen hours of truck operation are spent idling. Federal and Statelaws alike limit the number of hours that each truck driver can legallydrive a truck in a twenty-four hour period. During the remainder of thetime the driver must rest for the next available driving period. Restperiods are often spent in rest areas, truck stops or along the side ofan interstate. Trucks or tractors are often supplied with a “sleeper”for the driver to spend his or her rest time. Often the sleeper includesmodern amenities such as a television, VCR, DVD, satellite dish,refrigerator, air conditioner, coffee maker, even a microwave oven.While such items may run on direct current provided by an engine mountedalternator, or even alternating current by use of an inverter, the truckengine must remain running to prevent the discharge of the batteriesused for starting of the diesel engine. During idle a typical dieseltruck engine will burn about one gallon of diesel fuel per hour. Inaddition to the cost of the diesel fuel, normal maintenance costs to thetruck engine and its associated systems are increased.

In order to reduce fuel and maintenance costs, trucks often utilize anauxiliary generator to provide electrical power for systems within thetruck when the truck's engine is not running. The Applicant is a wellknown assembler of diesel engine/generators packages and has beenawarded patents for various arrangements. U.S. Pat. Nos. 5,765,805,6,047,942, 6,119,638, 6,677,684, 6,756,693 and 6,812,582 granted to theApplicant disclose combination engine/generator sets that arelightweight and of novel space saving configurations, the contents ofwhich are incorporated herein by reference.

The prior art also discloses numerous systems by which air conditioningand heating can be provided to the interior of a truck while the mainengine is not running. For example, U.S. Pat. No. 4,756,359 discloses anauxiliary power system that includes an auxiliary engine, electricalalternator, water pump, air conditioning compressor and heat exchanger.The heat exchanger is used to receive hot exhaust gases from theauxiliary engine for purposes of heating coolant routed through thetruck's engine.

U.S. Pat. No. 4,762,170 discloses an auxiliary power system for trucksor other heavy duty vehicles. The system includes an auxiliary enginesized to simultaneously power an air conditioner compressor and agenerator. The cooling system of the auxiliary engine is connected tothe cooling system of the truck's engine to keep the truck engine warmin cold weather.

U.S. Pat. No. 5,528,901 discloses an auxiliary power system whichincludes an auxiliary engine sized to power an air compressor, a waterpump, an A/C compressor and an oil pump. The system replaces theoriginal bank of batteries supplied with the truck and replaces the OEMelectric starter with a pneumatic starter.

Problems generally associated with the use of these prior art devicesrelate to size, weight, and placement of the systems. The size of anauxiliary generator is critical for vehicular use. If the overalldimensions are too large, there will be insufficient areas on a truckfor which to place the system. Other problems result from complexity ofinstallation and the costs associated therewith. Still other problemsresult from sharing coolant systems. Small engines rarely generateenough heat to maintain temperature within a large cooling system suchas those supplied with a large truck. As a result of the constant coldcylinder temperature the small engine runs inefficiently. Some systemsincrease the size of the auxiliary engine or place false loads on theauxiliary engines to increase heat transferred to the large engine'scooling system to maintain higher overall temperatures. However, thefalse loads and oversized engines decrease the overall efficiency ofthese systems. Other problems and expense are incurred with the use ofwater-to-water or water-to-oil heat exchangers. The heat exchangers areexpensive, difficult to install, and require each body of fluid to beequipped with an independent pump for fluid circulation.

It is also known to vary the output of a generator for specificapplications. For example, U.S. Pat. No. 4,099,067 discloses a controlfor diesel-electric motor-generator sets. The device allows temporaryoverloads to be accommodated without engine lugging by reducing linevoltage if an attempt is made to draw more than a preset maximum normalwattage. The line voltage reduction is accomplished by increasing theimpedance of the voltage regulator input circuit when a signal generallyproportional to line voltage and load current exceeds a preset referencesignal to which it is compared.

U.S. Pat. No. 5,512,813 discloses an A/C generator output controllingapparatus. The control device determines the field current to besupplied to a field coil on the basis of a voltage deviation between abattery charging voltage and a battery target voltage.

U.S. Pat. No. 5,739,677 discloses a vehicle power generating system. Thesystem includes a controller which varies the supply of leading phasecurrent supplied to the power generator. The system is particularlysuited for low RPM, high power generation.

U.S. Pat. No. 5,726,559 discloses a synchronous electric powergenerating apparatus and magnetization control method. Advance-phasecurrents are supplied to stator windings via semiconductor switchingdevices by controlling the semiconductor switching devices during powergeneration. The device and method are particularly suited to controlrotor temperature and reduce magnetic flux in an alternating currentpower generator.

U.S. Pat. No. 5,726,557 discloses a vehicular power system. The deviceincludes a rotating alternating current machine having polyphasearmature coils and a full wave rectifier for rectifying the generatedvoltage by a plurality of SiC-MOSFETs, to give a rectified output to thebattery unit. The device also includes a control device for selectivelyturning on the plurality of SiC-MOSFETs to raise the generated voltageby short-circuiting and open-circuiting the armature coils on the basisof the phases of voltage generated by the rotating alternating currentmachine.

These prior art devices are generally geared to maximizing the output ofa power generating device without overloading or overcharging theelectrical system of the vehicle. The engines utilized to drive thesedevices are generally of sufficient size to drive the generator at fullcapacity for extended periods. None of the prior art devices disclose orteach a system which is constructed to utilize a minimally sized engineto prioritize and drive alternative loads.

Thus, what is needed is an auxiliary power system that is lightweight,consumes a small space, and may be used to alternatively provideheating, electrical power or air conditioning to the interior of atruck. The auxiliary power system should be capable of shedding lowpriority demands for maximizing power supplied by the auxiliary engine.

SUMMARY OF THE INVENTION

The instant invention system includes a small diesel engine coupled toan air conditioner compressor, a generator or alternator and acombination control relay/regulator for maximizing the loads placed onthe auxiliary engine. The truck operator is provided with controls forselective operation of the auxiliary power system's various featureswhich may be operated while the truck's main engine is running orstopped.

In the preferred embodiment the auxiliary engine is sized so that it isnot capable of simultaneous operation of all the auxiliary systems totheir maximum capacity. In a most preferred embodiment the auxiliaryengine is rated from about three HP to about eight HP. Such engines arecurrently available from manufacturers such as KUBOTA, and may have ahorizontally or about vertically disposed cylinder.

One embodiment of the auxiliary power system includes a heating system.The heating system includes a water pump which may be electric ormechanically driven by the auxiliary engine. Operator controls permitthe water pump to circulate water through the auxiliary engine to asleeper heat exchanger, radiator or both. The heat exchanger may beremotely mounted within the interior of the truck to provide heat withinthe truck interior, and may further include an electric fan for forcingair across the heat exchanger to provide additional heat. The fan may beoperated via the driver's controls to regulate the amount of air passedacross the heat exchanger to provide warmth to the truck's interior.While the air conditioning compressor is turned off, via the driver'scontrols, the full capacity of the alternator or generator is availablefor the higher amp draws typical of cold weather where diesel enginesare harder to start and more electrical accessories are in use.

During hot weather operation the driver may utilize the controls tostart the auxiliary engine. The auxiliary engine may then be utilized tooperate an air conditioner compressor and related air conditioner systemcomponents, wherein the truck interior is kept cool. During this modethe auxiliary engine is also utilized to operate the alternator orgenerator to replenish power drawn from the truck batteries. In orderfor the auxiliary engine to provide power for both accessories, acontrol relay/regulator is utilized to switch the input field of thealternator, thereby reducing alternator output to maximize the poweroutput of the auxiliary engine. Should the truck accessories draw moreelectrical power than the alternator or generator supply during such apeak demand, the truck batteries operate as a reserve power source. Whenthe air conditioning compressor cycles off, the control relay/regulatorcauses the alternator or generator to increase electrical output toreplenish the truck batteries and supply electrical power to otheraccessories. In this manner the power output provided by the auxiliaryengine may be more fully utilized than in prior art power systems.

Thus, an objective of the instant invention is to teach an auxiliarypower system for trucks that utilizes a minimally sized engine toselectively operate air conditioning, heating and power generatingsystems.

Another objective of the instant invention is to teach a minimally sizedauxiliary power system for trucks capable of selectively providing airconditioning, heating, and electrical power to the interior area of thetruck.

Still another objective of the instant invention is to teach anauxiliary power system having a control relay/regulator constructed andarranged to maximize utilization of the power supplied by the auxiliaryengine.

Yet another objective of the instant invention is to teach an auxiliarypower system which includes a control relay/regulator constructed andarranged to maximize utilization of power supplied by an auxiliaryengine by controlled reduction of electrical power production forsimultaneous air conditioner compressor operation.

Still yet another objective of the instant invention is to teach anauxiliary power system which utilizes existing truck batteries as apower exchanger for peak accessory loads.

Another objective of the invention is to teach an auxiliary power systemfor trucks that captures heat from the engine coolant for warming of thetruck interior.

Yet another objective of the invention is to teach the use of anauxiliary power system that is inexpensive, small in size andlightweight.

Other objectives and advantages of this invention will become apparentfrom the following description taken in conjunction with theaccompanying drawings wherein are set forth, by way of illustration andexample, certain embodiments of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of the instant inventionauxiliary power system;

FIG. 2 is a diagrammatic representation of the instant inventionauxiliary power system used in conjunction with an under bunk heatingand air conditioning system; and

FIG. 3 is a diagrammatic representation of the instant inventionauxiliary power system in a heat providing mode.

DETAILED DESCRIPTION

Now referring to FIG. 1, a diagrammatic representation of one embodimentof the instant invention auxiliary power system 100 is illustrated. Theauxiliary power system generally includes an auxiliary engine 10 forselectively providing power to an electrical generation system 102, anair conditioning system 104, and a heating system 106. In the preferredembodiment the auxiliary engine is sized so that it is not capable ofsimultaneous operation of the air conditioning system and the electricalgeneration system to their respective full capacities. The auxiliarypower system includes a unique control relay/regulator combination 24,28 for reducing electrical power produced by the electrical generationsystem 102 during simultaneous operation of the air conditioning system104. This construction and arrangement permits the size and weight ofthe auxiliary power system to be substantially smaller than the powersystems of the prior art. The arrangement also permits the auxiliarypower system to utilize a small single cylinder diesel engine whichrequires less frequent oil change intervals than those required by thelarger engines of the prior art.

Referring to FIGS. 1-3, the auxiliary engine 10 is coupled to arefrigerant compressor, e.g. air conditioner compressor 12 and analternator 22. The air conditioner compressor is generally an automotivestyle compressor which includes a magnetic clutch, well known in theart, suitable for compressing any of the various refrigerants, also wellknown in the art. In one embodiment the compressor 12 is constructed andarranged to cooperate with the accumulator (not shown), expansion valve(not shown), evaporator 16, condenser 14 and air conditioner controls 18supplied with a truck.

In the preferred embodiment, a high output automotive style alternator22 is suitably coupled to the auxiliary engine 10 for rotation thereof.The alternator 22 may be based on 12 volts, 24 volts or other voltagedependant upon the trucks electrical system. In an alternativeembodiment, a generator may be utilized in place of the alternator 22 toprovide electrical current to various air conditioner support componentsand other accessories as well as batteries. The power produced by thealternator is available for operating accessories such as an alternatingcurrent inverter 20 connected to standard receptacles 30, allowing theoperation of household appliances such as razors, coffee makers,microwave ovens, alarm clocks, VCR's and so forth. Further 12 voltcomponents and accessories such as parking lights, interior lights,television, CB radio, sound system, refrigerator, and like devices, notshown, are all commonly used and require power for operation. Should thepower requirements be exceeded, due to peak draw devices such as amicrowave oven or coffee maker, the existing truck batteries 38 willproduce the necessary power by operating as a power sink.

In a most preferred embodiment, a single cylinder Kubota EL 300 ARengine capable of producing about four HP is coupled to a 12,000 BTU airconditioner compressor and a high output alternator 22 of about 120 ampson a 12 volt system. The size of the Kabota engine and the horizontalorientation of the cylinder allow the instant invention auxiliary powersystem 100 to be packaged into a small and lightweight add on device forthe trucking industry. In an alternative embodiment, a Kubota EA 300 NBengine capable of producing about seven HP may be coupled to, or rotatean air conditioner compressor at a higher rate, so as to produce about16,000 BTUs of air conditioning as well as simultaneously operate thehigh output alternator at reduced output. It is also contemplated thatother engines having vertically oriented cylinders and/or a larger poweroutput could also be utilized without departing from the scope of theinvention.

Load management control is provided by the control relay/voltageregulator combination 24, 28. The preferred embodiment utilizes anexternally mounted microprocessor controlled voltage regulator 28. Thevoltage regulator 28 is equipped with a reduced power setting, which istypically utilized to control alternator temperature in a marineenvironment. Such regulators are available from BALMAR Corp. ofArlington Va., model no. MC-612. The instant invention connects a relay24 between the positive and negative terminals of the temperaturecircuit provided with the regulator 28. When the relay switch 24 isactivated, the regulator 28 reduces the field current at the alternator22. Within the instant invention the control relay 24 is activatedduring operation of the air conditioning compressor 12. Activation ofthe relay reduces the output of the alternator by approximately 50% toreduce the load on the auxiliary engine 10, thereby allowing a smallengine to operate both systems simultaneously. As the air conditionerclutch disengages, control relay 24 also opens to allow higherelectrical production by the alternator 22.

It should also be noted that other regulators or regulation methods,well known in the art, that are suitable for controlled reduction ofalternator or generator electrical production in response to airconditioner compressor engagement may alternatively be utilized withoutdeparting from the scope of the instant invention.

Referring to FIG. 2, an alternative embodiment of the auxiliary powersystem is illustrated. In this embodiment the air conditioner compressorcooperates with an under bunk combination air conditioner and heaterunit 32. In this embodiment the accumulator, expansion valve,evaporator, condenser and air conditioner controls are contained withinthe under bunk unit. Under bunk heat and air conditioner units fortrucks are well known in the art.

Referring to FIG. 3, operation of heat system 106 is illustrated. Duringoperation of the heat system, water used to cool the auxiliary engine 10is circulated through a remotely mounted water to air heat exchanger 52by opening of a water valve 54. The engine coolant is fluidly coupled 42to the heat exchanger located in the evaporator/heater assembly 16 withan outlet 44 coupled to the radiator assembly 14 which is thencirculated back to the engine 10 by the water pump 40. Theevaporator/heater fan 17 may be turned on and used to draw air throughor across the heat exchanger for increased warming of the truckinterior. The electric radiator/condenser fan 26 cycles as required bythe temperature switch 27 to reduce auxiliary engine temperatures. Itshould be noted that by operating the auxiliary engine at its' optimumRPM's and operating the alternator at approximately 80% of fullelectrical load draw, the engine is operated at its most fuel efficientlevel and provides a fast and reliable heat source for the sleeper areaof the truck. The additional amperage draw may be used to power theparking lights, television, CB radio, refrigerator, AC inverter,interior lights and so forth necessary in cold weather operation. It hasbeen found that a block heater provides a unique false load to theengine causing the engine to operate at peak efficiency. The blockheater causing the engine temperature to reach its operating conditionquickly while the additional load placed on the engine results quickertemperature increase. Further, the use of a water cooled alternatorprovides a means to recover heat for delivery to the cab.

Referring to FIGS. 1-3, general operation of the auxiliary power systemwill be described. Upon start up of the auxiliary engine 10, the oilpressure within the auxiliary engine is checked via oil pressure switch20. If sufficient oil pressure is detected voltage is supplied to theauxiliary water pump 40 and relay 34. The auxiliary electrical systembecomes active and current from the battery is allowed to flow throughline 46 of regulator 28, and the alternator 22 begins to deliverelectrical power to the battery 38. For operation of the auxiliary airconditioning system 102, relay 34 is closed to allow electrical currentto flow to the air conditioning control 18. The air conditioner controlsare manipulated by the operator, e.g. driver, to control the auxiliaryheating system 106 and the auxiliary air conditioning. Should theoperator desire air conditioning the air conditioning controls 18 aremanipulated to cause the compressor 12 to engage the auxiliary engine10. Simultaneously, the control relay 24 closes to cause the voltageregulator 28 to reduce the output of the alternator 22. The airconditioner control also selectively operates the evaporator/heater fan17 and the condenser fan 26 as needed. A compressor clutch (not shown)remains engaged as long as the air conditioner pressure switch 48 isclosed, causing the compressor to cycle on and off as required toachieve the air conditioning control setting.

Should the operator desire to operate the auxiliary heat system, the airconditioner controls are manipulated to open the water valve 54 andstart the water pump 40. Water is then forced to flow through the heatexchanger 52 and optionally through the radiator 14 before returning tothe auxiliary engine 10. For increased heat, the fan 17 may be operatedto increase air flow over the heat exchanger. In this mode the controlrelay 24 generally remains open, allowing the alternator to produceelectricity to its full potential.

For purposes of simplification this application has been directed totrucks although it would be obvious to one of ordinary skill in the artto recognize that the teachings of this patent and the associated claimsmay be directed to buses, boats, ambulances and so forth. Further,alternator changes to address higher voltage systems may be substitutedthroughout this specification and considered an obvious variation withinthe scope of the patent. It is to be understood that while I haveillustrated and described certain forms of my invention, it is not to belimited to the specific forms or arrangement of parts herein describedand shown. It will be apparent to those skilled in the art that variouschanges may be made without departing from the scope of the inventionand the invention is not to be considered limited to what is shown inthe drawings and described in the specification.

1. An auxiliary power system for use in trucks comprising: an auxiliaryengine for selectively providing power to an electrical generationsystem and an air conditioning system, said auxiliary engine being sizedso that it is incapable of simultaneous operation of said airconditioning system and said electrical generation system to theirrespective full capacities; a control relay/regulator for reducingelectrical power supplied by said electrical generation system duringsimultaneous operation of said air conditioning system, whereby powersupplied by said auxiliary engine is maximized.
 2. The auxiliary powersystem according to claim 1 wherein said auxiliary power system includesa heating system.
 3. The auxiliary power system according to claim 2wherein said heating system includes a water cooled auxiliary engine, awater pump and a remotely mounted heat exchanger, wherein said heatexchanger is mounted within a truck cabin area to selectively provideheat thereto.
 4. The auxiliary power system according to claim 3 whereinsaid water pump is mechanically driven by said auxiliary engine.
 5. Theauxiliary power system according to claim 3 wherein said water pump iselectrically driven, wherein said electrically driven water pump may beselectively operated.
 6. The auxiliary power system according to claim 1wherein said electrical generation system includes an alternator,wherein said alternator is operably coupled to said auxiliary engine forrotation thereof.
 7. The auxiliary power system according to claim 6wherein said alternator is capable of producing about 120 amperes. 8.The auxiliary power system according to claim 3 wherein said electricalgeneration system includes a generator, wherein said generator isoperably coupled to said auxiliary engine for rotation thereof.
 9. Theauxiliary power system according to claim 6 wherein said generator iscapable of producing about 120 amperes.
 10. The auxiliary power systemaccording to claim 1 wherein said control relay/regulator is externallymounted with respect to said alternator.
 11. The auxiliary power systemaccording to claim 1 wherein said control relay/regulator is constructedand arranged to reduce electrical production of said electricalgeneration system by about one half during operation of said airconditioning system.
 12. The auxiliary power system according to claim11 wherein said control relay/regulator is constructed and arranged toreduce electrical production of said electrical generation system fromabout 120 amperes to about 60 amperes during operation of said airconditioning system.
 13. The auxiliary power system according to claim10 wherein said regulator is a microprocessor controlled voltageregulator equipped with a half power temperature control circuit. 14.The auxiliary power system according to claim 13 wherein said regulatoris a BALMAR model no. MC-612.
 15. The auxiliary power system accordingto claim 13 wherein said relay is connected between a positive terminaland a negative terminal provided with said temperature control circuitof said regulator, whereby closing said relay causes said regulator toreduce a field current within said alternator thereby reducing output ofsaid alternator.
 16. The auxiliary power system according to claim 1wherein said air conditioning system includes a compressor operablyconnected to said auxiliary engine for selective rotational operation.17. The auxiliary power system according to claim 16 wherein saidcompressor includes a magnetic clutch for selective operation of saidcompressor.
 18. The auxiliary power system according to claim 1 whereinsaid air conditioner compressor produces about 12,000 BTU and saidauxiliary engine produces about four horsepower.
 19. The auxiliary powersystem according to claim 18 wherein said engine is a four HP KUBOTA EL300 AR.
 20. The auxiliary power system according to claim 1 wherein saidair conditioner compressor produces about 16,000 BTU and said auxiliaryengine produces about seven horsepower.
 21. The auxiliary power unitaccording to claim 20 wherein said engine is a seven HP KUBOTA EA 300NB.
 22. The auxiliary power system according to claim 16 wherein saidtruck includes an air conditioning system, wherein said auxiliary airconditioning system is connected to utilize at least a portion of saidtruck's air conditioning system.
 23. The auxiliary power systemaccording to claim 22 wherein said truck air conditioning systemincludes an accumulator, an expansion valve, an evaporator and acondenser, wherein said auxiliary air conditioning system utilizes saidtruck accumulator, expansion valve, evaporator and condenser.
 24. Theauxiliary power system according to claim 1 including an electricalinverter, wherein said electrical inverter is constructed and arrangedto provide alternating electrical power for operation of truckaccessories.